NF ISO 11929-4, M60-200-4 (09/2022)

This document specifies a procedure applicable, in the field of ionizing radiation metrology, for the calculation of the "decision threshold", "detection limit" and "extended range limits" for a radiation measurand non-negative ionizing, when counting measurements are carried out with a preselection of time or number of pulses. The measurand results from a raw count rate and a background count rate as well as additional quantities based on an evaluation model. In particular, the measurand may be the net count rate defined as the difference of the raw count rate and the background count rate, or the net activity of a sample. It can also be influenced by the calibration of the measuring system, by sample processing and other factors. ISO 11929 has been split into four parts covering basic applications in ISO 11929-1, advanced applications based on ISO/IEC Guide 98-3:2008/S1 in ISO 11929-2, applications to deconvolution methods in ISO 11929-3, and application recommendations in ISO 11929-4. ISO 11929-1 covers the basic applications of counting measurements often used in the field of ionizing radiation metrology. It is limited to applications for which uncertainties can be assessed on the basis of ISO/IEC Guide 98-3 (JCGM 2008). ISO 11929-1:2019, Annex A deals with the special case of repeated counting measurements with random influences, while ISO 11929-1:2019, Annex B covers measurements with linear analog ictometers. ISO 11929-2 extends ISO 11929-1 to the assessment of measurement uncertainties in accordance with ISO/IEC Guide 98-3:2008/S1. ISO 11929-2 also contains several explanatory notes concerning general aspects of counting measurements and Bayesian statistics in measurements. ISO 11929-3 deals with the evaluation of measurements using deconvolution methods as well as the evaluation of multichannel spectrometric measurements by counting when evaluated by deconvolution methods, in particular for alpha and gamma. It further provides guidance for processing with correlations and covariances. ISO 11929-4 provides guidance for the application of ISO 11929 (all parts), summarizes the general procedure, and then presents a wide range of numerical examples. The examples cover basic applications according to ISO 11929-1 and ISO 11929-2. ISO 11929 (all parts) also applies analogously to other measurements of any type if a similar evaluation model is concerned. Further practical examples are provided in other International Standards (see References [1 to 20] for example). NOTE Software, called UncertRadio, is available for calculations in accordance with ISO 11929-1 to ISO 11929-3. UncertRadio[40][41] can be downloaded free of charge at: https://www.thuenen.de/en/fi/fields-of-activity/marine-environment/coordination-centre-of-radioactivity/uncertradio/ . The software available for download contains an installation file that copies all files and folders to a user-specified location. After installation, information must be entered regarding the Windows PATH that was given in a pop-up window during installation. English language can be chosen and extensive help information is offered. Another tool is the software package “metRology”[44] which is available for programming in the R language. It contains the two R functions “uncert” and “uncertMC” which ensure the propagation of uncertainties according to the GUM, either analytically or after the Monte Carlo method, respectively. Covariances/correlations of input quantities are included. Applying these two functions in the iterations intended for calculations of the decision threshold and the detection limit considerably simplifies the programming effort. It is also possible to implement this document in a spreadsheet containing a Monte Carlo addendum or in other commercial mathematics software.
(Automatic translation from French)